Over the past few years, there has been an explosive growth of interest in research and industrial applications for transparent conductors. A transparent conductor typically includes a transparent substrate upon which is disposed a coating or film that is transparent yet electrically conductive. This unique class of conductors is used, or is considered being used, in a variety of applications, such as solar cells, antistatic films, gas sensors, organic light-emitting diodes, liquid crystal and high-definition displays, and electrochromic and smart windows, as well as architectural coatings.
Conventional methods for fabricating transparent conductive coatings on transparent substrates include dry and wet processes. In dry processes, plasma vapor deposition (PVD) (including sputtering, ion plating and vacuum deposition) or chemical vapor deposition (CVD) is used to form a conductive transparent film of a metal oxide, such as indium-tin mixed oxide (ITO), antimony-tin mixed oxide (ATO), fluorine-doped tin oxide (FTO), and aluminum-doped zinc oxide (Al—ZO). The films produced using dry processes have both good transparency and good conductivity. However, these films, particularly ITO, are expensive and require complicated apparatuses that result in poor productivity. Other problems with dry processes include difficult application results when trying to apply these materials to continuous and/or large substrates. In conventional wet processes, conductive coatings are formed using the above-identified electrically conductive powders mixed with liquid additives. In all of these conventional methods using metal oxides and mixed oxides, the materials suffer from supply restriction, lack of spectral uniformity, poor adhesion to substrates, and brittleness.
Alternatives to metal oxides for transparent conductors include conductive components such as, for example, silver nanowires and carbon nanotubes. Transparent conductors formed of such conductive components demonstrate transparency and conductivity equal to, if not superior to, those formed of metal oxides. In addition, these transparent conductors exhibit mechanical durability that metal-oxide transparent conductors do not. Accordingly, these transparent conductors can be used in a variety of applications, including flexible display applications. However, the transparency and conductivity of transparent conductors fabricated using conductive components depends on the process by which the conductors are made.
Accordingly, it is desirable to provide methods for fabricating transparent conductors with enhanced transparency and conductivity. In addition, it also is desirable to provide such transparent conductors that do not require expensive or complicated systems. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.